Reasons why tar does not accumulate in the fully filled ammonium sulfide trough
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Recently, the color of ammonium sulfate has turned black. I tried to find out the cause of this discoloration, starting by examining the tar that accumulates in the flow tank where ammonium sulfate is stored. However, no tar accumulates in that tank, so it’s not possible to collect any sample from there. I would like to ask everyone what could be causing this issue
1. It’s available on the forum; please search for it. Mainly acid tar and sulfonates. 2. If the color of the ammonium sulfate produced is light, and the color of the mother liquor is also light, please try increasing the acidity of the mother liquor as well as its specific gravity. In this way, the acidic tar can be gathered together. 3. If the color of the mother liquor is very dark, and the ammonium sulfate product obtained is also gray or black, it is recommended that the person in question prepare the solution again.
First, let’s analyze the issue of ammonium sulfate turning black: to determine the exact color, there are significant differences, as the reasons for turning black, brown, or gray are various. If the color of the mother liquor also changes, the difference from a situation where the mother liquor color remains unchanged is significant. Simply saying that the acidic tar does not accumulate in the tank might be due to a low acidity level of the mother liquor, while the tar content in the gas is high; as a result, there is plenty of acidic tar in the tank and it does not tend to accumulate. It would be advisable to increase the acidity level and observe the situation.
Our factory has encountered a similar situation as well: the acidity level rose above 4% yet the problem wasn’t resolved, and the specific gravity exceeded 1.28. I think the desulfurization liquid containing tar from the desulfurization tower has ended up in the main liquid; it seems that the tar has been emulsified, making it difficult to separate the layers. Every time we improve the color by adding acid and water, it turns gray again after a few days, which is really frustrating
Tar is mainly composed of oligomers; the higher its degree of polymerization, the more likely it is to aggregate. In your case, it might be advisable to design the ammonium sulfide tank in a manner similar to a liquid-liquid separator, with ammonium sulfide being discharged from the bottom, while the tar remains in the upper layer – it can then be removed when it accumulates enough. Furthermore, to ensure the quality of your ammonium sulfate and to guarantee that there are no tar substances in it, as tar is an organic compound with a complex composition, including it in ammonium sulfate as a fertilizer could potentially affect the safety of crops. Therefore, it is advisable to use activated carbon to absorb tar and other organic substances from the ammonium sulfate solution before processing it into solid ammonium sulfate products.
Recently, after increasing the production capacity of our coke ovens, the color of the mother liquor in the full-flow tank has turned severely dark; there is no accumulation of tar, and no cause could be identified
Is the fact that tar does not polymerize related to the temperature of the mother liquor?
The non-polymerization of tar has nothing to do with the temperature of the mother liquor; the key factor is the acidity of the mother liquor. It is possible that a low acidity level results in a lower specific gravity of the mother liquor, and this condition also tends to cause foaming in the mother liquor.
The last edit to this post was made by Yixin Yiyi777 on 2009-7-4 at 20:19. The main measures include increasing acidity and raising the specific gravity of the mother liquor; acid should be added in large quantities regularly to prepare the mother liquor. It is also important to lower the temperature of the gas after initial cooling, thereby improving the tar removal efficiency of the electrostatic precipitator； When desulfurization is carried out, attention should be paid to the performance of the desulfurization mist capture device to prevent excessive entrainment of sulfur foam.
Increasing the specific gravity of the mother liquor to above 1.3 can solve this problem